Terephthalic acid/1,2-propylene glycol polyester modifiers for polyvinyl chloride compositions

ABSTRACT

Plastic compositions based on poly(alkylene terephthalates), in particular poly(1,2-propylene terephthalate) polyesters intermixed in polyvinyl chloride compositions, are provided. The compositions of this invention provide improved processing characteristics with reduced melt viscosity and improved physical and mechanical properties such as tensile properties and weathering resistance.

United States Patent 1151 3,686,361 De Witt, III et al. 5] Aug. 22, 1972 1541 TEREPHTHALIC ACID/1,2- 3,427,287 2/1969 Pengilly ..260/475 1 PROPYLENE GLYCOL POLYESTER 3,448,173 6/1969 Ryan et a1 ..260/876 MODIFIERS FOR POLYVINYL 3,520,844 7/1970 Pontius et a1. ..260/873 CHLORIDE COMPOSITIONS FOREIGN PATENTS OR APPLICATIONS [72] Inventors: Walter Groesbeck De Witt, Ill, 1182 Strathmann Dr" Southampton, p 506,962 11/1954 Canada ..260/873 8966; Jmph Hum", OTHER PUBLlCATlONS 8267 Thomson Rd., Elkins Park, Pa.

22 Filed: April 15, 1969 [21 Appl. No.2 816,419

260/475 P 511 1111.01 ..C08f 29/24, C08g 17/06, C08g 39/10 [58] Field 61 Search ..260/873, 31.6, 75 R, 475 P [56] References Cited UNITED STATES PATENTS 2,386,405 10/1945 Meincke ..260/31.6 3,148,200 9/1964 MillS et al. ..260/31.6 3,392,135 7/1968 HOlUb et a1. ..260/31.6 3,041,309 6/1962 Baer ..260/45.5 3,288,886 11/1966 Hemei et a1. ..260/876 3,331,802 7/1967 Huber et al ..260/475 P British Plastics, Feb. 1959, High Mol. Wt. Plasticizers for P.V.C., Hill pp. 74- 77 and 89.

Primary Examiner-William l-l. Short Assistant ExaminerEdward Woodberry Att0meyCarl A. Castellan and George W. F. Simmons ABSTRACT Plastic compositions based on poly(alkylene terephthalates), in particular poly(1,2-propylene terephthalate) polyesters intermixed in polyvinyl chloride compositions, are provided. The compositions of this invention provide improved processing characteristics with reduced melt viscosity and improved physical and mechanical properties such as tensile properties and weathering resistance.

8 Claims, N0 Drawings TEREPHTHALIC ACE] l ,Z-PROPYLENE POLYESTER MODIFERS FOR POL lass of polyesters and their use in polyvinyl chloride plastic compositions. Polyvinyl chloride compositions include, but are not limited to, polyvinyl chloride, copolymers of vinyl chloride, polyvinyl chloride polymers with modifying compounds, halogenated polyvinyl chloride, and plasticized vinyl chloride compositions. This invention further relates to poly(alkylene aryl dicarboxylates) such as polyalkylene phthalates, in particular certain polyalkylene terephthalates. Of particular preference is poly( 1,2-propylene terephthalate) and its use in vinyl compositions. The inclusion of these polyesters in polyvinyl chloride compositions yields many advantages including greatly increased flow at melt temperatures, that is, processing temperatures, without significantly affecting the physical characteristics at normal service temperatures, improved impact strength or tensile properties in rigid extruded polyvinyl chloride sheet compositions, improved mechanical properties in plasticized vinyl compositions as well as many other unexpected qualities.

Polyvinyl chloride, hereinafter referred to as PVC, is widely used in the production of plastic articles. For most all uses PVC must be modified, compounded or copolymerized with other materials to provide processable and useful compositions. For the purpose and scope of this specification the term polyvinyl chloride compositions or PVC compositions will include all compositions which have vinyl chloride as the major (greater than 50 percent) component or starting material. The PVC compositions include, but are not limited to: PVC, copolymers of vinyl chloride with other monomers that include vinyl alkanoates such as vinyl acetate and the like, vinylidene halides such as vinylidene chloride, alkyl esters of carboxylic acids such as acrylic acid like ethyl acrylate, 2-ethylhexyl acrylate and the like, unsaturated hydrocarbons such as ethylene, propylene, isobutylene and the like, allyl compounds such as allyl acetate and the like; modified versions of the above polymers for impact strength with such modifiers as acrylic elastomeric impact modifiers, butadiene copolymers and the like, for processability, for example, on rolling banks with such materials as acrylic polymers such as copolymers of methyl methacrylate and ethyl methacrylate, for flexibility with such materials as plasticizers such as dioctyl phthalate, poly(propylene adipate) and the like, and other modifiers such as chlorinated polyethylene; and many others. The molecular weight and molecular weight distribution of the PVC polymers in the PVC compositions is not critical to the aims, purposes and results of using this invention. For general applications PVC with Fikentscher K-values in the range of 40 to 95 are generally used. The Fikentscher K-value is determined by the formula where C is a constant concentration of polyester in solvent equaling 05 gm/ 100 ml, 1; rel is relative viscosity in cyclohexanone at 25 C., and K is Fikentscher Value.

This copolymerization and compounding of these PVC compositions is necessary due to limitations of PVC. As an example, one of these limitations is the difficulty encountered in processing PVC at elevated temperatures. Mill processing on rolling banks may be improved and a partial remedy has already been mentioned-the acrylic copolymer processing aid. Acrylic copolymer processing aids improve the rolling bank and other processing characteristics of PVC compositions during mill processing, but usual fabrication temperatures for rigid PVC compositions can lead to thermal degradation of these compounds during extended fabrication periods. At the temperature of extrusion, injection, therrnoforming, blow molding and the'like, PVC compositions tend to degrade due to the relative heat instability of PVC and PVC compositions. It would be most desirable if PVC compositions could be processed in operations such as extrusion, injection molding, therrnoforrning, blow molding, and the like at lower temperatures or with shorter cycle times, thereby minimizing the change for thermal degradation. Certain compounds such as common plasticizers, that flexibilize the compositions at service temperatures, reduce the melt viscosity of PVC, but the inclusion adversely affects many of the physical properties or rigid compositions such as resistance to deformation at elevated temperatures. This is only one deficiency now alleviated by the invention, but it serves to demonstrate the state of the art at least in one part of the field of utility of the invention.

It now has been discovered that certain polyesters form useful homogeneous compositions in PVC and PVC compositions. It has now been further discovered that the incorporation of these polyesters in PVC compositions elirninates-or at least greatly improves upon-many of the deficiencies of these materials. For example, the difficulties encountered due to high temperature instability of PVC described above are essentially eliminated by the incorporation of the polyesters. These polyesters act to improve the processing characteristic and as a melt viscosity reducer. Further, the inclusion of these polyesters does not adversely affect the individual physical properties of PVC compositions to any significant degree. In fact, many of the physical properties of the compounds are improved by the inclusion of these polyesters. Other deficiencies of PVC compositions and the beneficial effects obtained by including the polyesters of this invention will be clear upon reading the specification.

The polyesters of this invention are poly(alkylene terephthalates) that may be described by formula (I):

wherein A is the residue of a terephthalic acid or mixtures of dibasic acids selected from the group con sisting of terephthalic acid and other dibasic acids, wherein A is at least mole percent terephthalic acid,

G is the residue of 1,2-propylene glycol or mixtures of diols, wherein G is at least 75 mole percent 1,2- propylene glycol, and m is an average number greater than about 2.0; where m in formula (I) is relatively small and the molecular weight is consequently small, the acid functionality as a terminal group does affect the compatibility of the polyester in PVC compositions. Also, particularly when the hydroxy substitutions of a glycol are on a secondary carbon atom, it is more difficult to prepare high molecular weight polyesters with terminal acid'functionality. It is preferredthat the acid functional terminal groups be covered in some manner. This may be accomplished by the use of excess glycol or by esterifying the acid termination of the polyester with an alcohol such as ethanol, undecanol, and the like. Preferred polyesters of this invention are glycolterminated polyesters of formula (II):

1. hereinbefore and n is an average number. greater than about 1.0. The glycol terminated polyester of formula (H) is more easily prepared and yields the preferred balance of physical characteristics in PVC compositions.

other diols may include, butare not limited to,

alkylene glycols such as ethylene glycol diethylene glycol triethylene glycol,

higher polyethylene glycols,

1,3-propylene glycol dipropylene glycols,

higher polypropylene glycols,

1 ,3-butylene glycol,

1,4-butylene glycol,

neopentyl glycol,

1,5-hexalene glycol, and substituted versions of these alkylene glycols and the like; cycloalkylene glycols such as 1 ,2-cyclopentanediol,

l ,3-cyclopentanediol,

l ,2-cyclohexanediol,

1 ,3-cyclohexanediol,

1 ,4-cyclohexanediol,

cyclobutanediols,

cyclobutanedimethanol,

cyclohexanedimethanol, substituted versions of these cycloalkylene glycols and the like; and aryl glycols such as the ethylene oxide or propylene oxide adducts of para, para-isopropylidenediphenol and the like. It is preferred that up to 25 mole percent of the residue of 1,2-propylene glycol be replaced with the residue of other glycols, in particular those containing 2 to 4 carbon atoms.

It is preferred that A and G be selected to provide polyesters with linearity and high glass temperatures. This may be obtained by utilizing major quantities of terephthalic acid in the preparation of the polyester.

The other residues of dibasic acids in admixture with terephthalic acid include but are not limited to aryl and alicyclic dicarboxylic acids, such as isophthalic acid, orthophthalic acid or anhydride, naphthalene dicarboxylic acid or anhydride, cyclohexyl dicarboxylic acids or anhydrides, cycloheptane dicarboxylic acids or anhydrides, substituted aryl and alicyclic dicarboxylic acids or anhydrides, such as halogenated aryl dicarboxylic acids or anhydride like hepta-, chloro, phthalic anhydride,

alkylene substituted aryl dicarboxylic acid or anhydrides,

. .0 1 wherein A and G have the same meaning described As indicated hereinbefore, G is the residue of 1,2- propylene glycol or mixtures with other diols. These endoalkylene substituted aryl carboxylic acids and substituted versions like 1,4,5,6,7,7-bicyclo(2.2. l )-5- heptane-2,3-dicarboxylic acid, and the like.

In regard to suitable polyesters of this invention, it has been found that for rigid non-plasticized PVC compositions the preferred chemical compositions within the chemical description of the polyesters of this invention is broader in view of the substantial effects on the physical characteristics. For plasticized PVC compositions the suitable chemical compositions of the polyesters is somewhat more limited. Unusual effects are obtained in rigid non-plasticized PVC compositions when other aryl dicarboxylic acids are used.

It has been found that in rigid, non-plasticized PVC compositions wherein rigidity and resistance to deformation at elevated temperatures are important characteristics, the polyester chosen is preferred to have an amorphous, glassy, softening point in the range of 65 to 200 C. It is more preferred that the softening point fall in the range of 65 to 120 preferred that the polyester have a softening. point in the range of 75 to 100 C. This amorphous, glassy softening point is determined by placing chips of the polyester on a melting point block which is heated such that the temperature of the block is increased at the rate of about 2 C./rninute. The softening point is determined when the chips either turn soft or when chips stick together. Of particular preference is poly(propylene terephthalate), hereinafter referred to as PGT, in that over the entire molecular weight range presently obtainable, great utility is found in PVC com- P si s- The polyesters of this invention at all molecular weights obtainable under present technology are effective in PVC compositions. However, for a given PVC composition or particular balance of characteristics desired, specific molecular weight ranges are preferred. For example, in PGT modified compounds, as the molecular weight of PGT is increased, the impact strength is generally improved. For this effect it is preferred that the polyester have a number average molecular weight greater than about 4,000 and, more preferably, greater than about 7,000. Throughout this specification the term molecular weight refers to the number average molecular weight as determined by ebulliometric techniques. No upper limit of molecular weight is known as to the utility of PGT in PVC; however, for practical purposes a molecular weight less than about 20,000 is preferred and less than about 17,000 is more preferred. When PGT is utilized in PVC compositions primarily to improve processing behavior through the reduction in the melt viscosity, a molecular weight range of about 1,200 to 4,000 is preferred, and

about 1,300 to 2,500 is most preferred, since maximum when n of formula (II) is approximately 1.0. In these plasticized systems molecular weights of PGT are C., and it is most generally kept below 2,500 to limit the increase in rigidity and a range of 800 to 1,500 is preferred. Therefore, it will be clear from this, and the examples provided later, that certain molecular weight ranges are preferred for certain compositions and to attain certain physical characteristics, but there is essentially no limit on the molecular weight of the polyesters useful in PVC compositions. Generally, the greatest utility for these polyesters is obtained when the polyester molecule contains at least two repeating units of the residue of the glycol and the dibasic acid; that is, when m is 2.0 or more in formula (I). The preferred range of molecular weight of the polyester is 400 to 20,000.

The polyesters of this invention may be prepared by several synthetic methods such as bulk, solution and interfacial condensation procedures. The polyesters may be obtained through esten'fication of the glycol mixture with the dibasic acid mixture with heat and catalysts such as metal salts of lead, tin, calcium, zinc and antimony along with organometallic compounds derived from such metals as tin and titanium. Alternatives for the terephthalic acid or isophthalic acid, which are somewhat intractable, are the lower alkyl esters of the dibasic acid and utilizing a transesterification reaction. The chloride of terephthalic acid may also be used. For example, PGT may be prepared as follows:

A two-liter resin kettle equipped with a close-fitting spiral double-flight stirrer, a nitrogen bubbler and a distillation column consisting of a steam jacketed column and a Dean-Stark take-off trap is placed in an oil bath at 160 C. A charge of 1,000 grams of dimethylterephthalate, 876 grams propylene glycol and 5 grams litharge is placed in the kettle. As the oil bath temperature is increased towards 230 C., the reactants gradually become clear and methanol evolves, indicating transesterification has begun. The temperature of the oil bath is maintained at 228230 C. for a period of approximately 250-300 minutes during which about 85-94 percent of the theoretical amount of methanol is recovered. At that time the nitrogen bubbler is replaced with a vacuum-tight inlet valve and the distillation column is replaced by a water-cooled distillation head connected to a dry-ice isopropanol cooling receiver. The pot temperature is allowed to cool to 210 C. and vacuum is slowly applied so that the rate of distillation of the excess propylene glycol is well controlled. After two hours the system is placed under high vacuum and maintained at 0.2 mm. Hg. with a slow nitrogen feed until a Gardner-Holdt viscosity (25 percent in tetrachloroethane) of N to P is obtained. During the total reaction time of six hours the amount of distillate obtained under vacuum is about 450 to 500 grams. As the reaction vessel is brought to atmospheric pressure, a strong nitrogen flow is applied. The physical characteristics of the PGT include:

Hydroxyl Number (mg. KOl-I/gm PGT) 12.5 13.5 Acid number (mg. KOH/gm PGT) 2.8 3.5 Iodine Number (gm.l,jl gm PGT) 0.4 0.6 Water Content (Karl-Fischer Method) 0.03% Yield 2.2 lbs. Molecular Weight 8000 The molecular weight of the polyester may be adjusted by stopping the reaction at the desired viscosity. Thus, a low molecular weight PGT may be obtained with charges of 876 grams propylene glycol and 856 grams terephthalic acid. The reaction is run at temperatures up to 187 C. and a vacuum is applied towards the end of the reaction, after about 23 hours. A sample of PGT with Gardner-Holdt viscosity of about A-4 (25 percent in tetrachloroethane), with a V.C.S. color of 1 and a molecular weight of about 900 is obtained.

The following examples are supplied to demonstrate how the polyesters of this invention may be used in some of the preferred embodiments of the invention. In no way should these examples be taken to limit the scope or the underlying principles of the invention in any way. Only some of the advantages and improvements obtained will be mentioned, but one skilled in the art will be able to appreciate many more embodiments of the invention from these examples. The following abbreviations will be used and those already mentioned will be repeated for convenience. Percentages are by weight unless otherwise noted:

PVC polyvinyl chloride a number following will characterize the molecular weight by the Fikentscher Kvalue system a number in parenthesis following these abbreviations will refer to the number average molecular weight use X 10'.

poly(propylene sebacate) dioctyl orthophthalate deformation temperature under load in C. using ASTM Procedure D-648-56 n melt viscosity poise at 400 F.

X l0 sec.

number average molecular weight EXAMPLE 1 The samples discussed are all fluxed on a two-roll barrel mill at 350 F. and pressed at 350 F. into mil sheets for testing. Unless otherwise noted, 1 percent of a commercially available tin stabilizer, dibutyltin mercaptopropionate and one-half percent of a lubricant, such as glycerol monostearate, is incorporated into the compound.

a. Sheets of PVC(68) are prepared with portions of the PVC replaced with the concentrations of the additives shown in Table I below:

TABLE I PGT PGS DOP DTUL copolymer of 80 parts methyl methacrylate and 20 parts ethyl methacrylate These data clearly show that PGT reduces the melt viscosity without affecting the DTUL to a significant degree. On the other hand, the acrylic processing modifier hardly affects the melt viscosity while the common plasticizers severely reduce the DTUL.

b. Sheets of 80 percent PVC (68) and 20 percent PGT of varying molecular weights are shown in Table II. This table shows that molecular weight of the polyester additive hardly affects the DTUL over a wide range, but the melt viscosity is greatly reduced as the molecular weight of the polyester is lowered.

TABLE II Effect of PGT of Various Molecular Weights on PVC Properties of Sheets PGT Melt Viscosity Vicat Gardner- M, of (poise, at 400F.; DTUL, Temp. Holdt Viscosity* PGT 10 sec.) (C.) (C.)

None None 7,000 73 85 T-U 13,200 6,700 74 85 AB 2,520 5,200 71 79 A 1,380 4,600 73 78 A, 860 4,200 65 72 A, 3,700 51 62 25% in tetrachloroethane 0. Sheets of PVC (68) with varying concentrations of PGT (1,400) and PGT (850) are shown replacing (1. Sheets of 80% PVC (68) and 20 percent of the additive as indicated are prepared as shown in Table IV below:

TABLE IV Effect of Modifiers on the Physical Properties of PVC Poly (propylene sebacate) 350,000 45 255,000 210.2 5758 D0? 90,000 190.6 4167 DCHP 330,000 50 *Dicyclohexylphthalate, solid plasticizer These data clearly show that the PGT modified PVC has similar physical characteristics to the unmodified PVC provided the M of PGT is greater than about 850 while conventional plasticizers display completely different physical characteristics in PVC compositions.

e. A sheet of PVC (68) and 20% PGT (1 ,400) is prepared with 3 percent of a standard barium-cadmium soap heat stabilizer. When tested in comparison with unmodified PVC, the PGT modified compound had significantly more resistance to heat degradation at 350 F. as shown in Table V below.

TABLE V Effect of PGT on Heat Resistance, Clarity and Crease Whitening Resistance Hours to Hours to Total Crease %PGT Color at Char at White Light Whitening 1400) Resisttance 350 F. Trans- %Haze mittance(%) 1 A greater 69.0 21.8 5

than 5 *Based on a relative scale of 0-1 0 where 0 is considered excellent The inclusion of PGT improves the heat resistance,

.clarity and the crease whitening resistance of PVC depending upon the choice of heat stabilizer.

f. In milled/pressed sheets the inclusion of PGT in PVC does not appear to detract significantly from the impact resistance as shown in Table VI.

TABLE VI Effect of Molecular Weight of PGT on Impact Strength 2. As indicated hereinbefore, processing modifiers are generally necessary for commercial production. Under the small-scale test conditions of Example 1, the unmodified PVC may be formed into sheets but such unmodified formulation would not be generally commercially useful. Therefore the comparison between a composition containing an acrylic processing modifier that is capable of being used with commercial extrusion techniques and a composition of this invention is most relevant. The lowering of the melt viscosity by the use of the invention has been demonstrated earlier. The effect on the inclusion of PGT on falling dart impact strength of PVC (68) is shown in Table VII.

3. In plasticized compositions the physical and mechanical properties at a given hardness may be somewhat deficient. The inclusion of PGT In plasticized PVC compositions improves the tensile strength and the tear strength of the sheet. The use of PGT also improves the thermoformability of plasticized sheet by reducing the shrinkage upon aging after forming. These valuable improvements are demonstrated on Table VIII and IX. The following compositions, the properties of which are listed in Table VIII, are milled at 350 F. for 10 minutes to prepare the sheet.

Parts PVC (73) 80 PGT 1400) as shown poly(propylene sebacate) as shown trioctyl trimellitate 60 to 65 as shown calcium carbonate powder 50 titanium dioxide (RANC) elastomeric impact modifier 20 barium/cadmium laurate heat stabilizer 2 *impact modifier a graft polymer of alkyl methacrylate such as methyl methacrylate polymerized in the presence of butadiene/styrene elastomer.

TABLE VIII Effect of PGT on Physical Propert1es of Plasticized PVC Compositions Composition Trioctyl trimellitate 60 65 60 60 PGT (1400) O O O Poly(propy1ene sebacate 10 Physical Properties Shore A-Z Hardness sec. 77 77 79 73 Tensile strength (psi) 1926 1730 1836 1643 Elongation at break 390 385 374 380 Tear strength (lb/in thickness) with calendar 235 204 213 197 against calendar 266 238 241 220 Vacuum Forming (%shrinkage after 16 hrs. at RT/S min. at 180 F.

Forming temperature: 300F. with ca1endar1.6/2.7 1.9/2.91.8/4.1 1.2/2.3 300F. against cal. 1.7/2.9 2.5/3.3l.7/3.6 1.9/3.3 320F. with calendar1.6/2.3 1.6/2.50.8/2.3 1.6/2.5 320F. against cal. 1.7/1.9 2.1/2.31.0/2.1 1.3/2.1

The following compositions, milled for 10 minutes at 350 F. and pressed into sheets, give the physical characteristics shown in Table IX.

Parts PVC 73) 80 Elastomeric impact modifier of Example 3 20 PGT (Mn as shown) 10 Trioctyl trimellitate plasticizer 60 Calcium carbonate powder 50 Titanium dioxide (RANC) 5 Barium/cadmium laurate heat stabilizer 2 TABLE IX Effect of PGT at Various Molecular Weight on Plasticized PVC Composition Mn of PGT 850 1400 2500 Shore A Hardness 15 sec. 73 78 78 Tensile strength (psi) 1672 1796 1806 Elongation at break 388 370 390 Tear strength (1b./in. thickness) with calender 195 227 233 against calender 280 257 271 Vacuum forming shrinkage after 16 hrs. at RT/5 min. at 180 F.) Forming Temperature: 300 F. with calender 1.0/2.5 1.0/2.3 12/2.7 1.8/3.5 300 F. against calender 1.0/1.9 1.3/2.9 1.3/2.5 2.3/3.6 320 F. with calender 0.6/1.4 0.8/1.9 0.8/1.6 1.2/2.3 320 F. against calender 4. The inclusion of PGT in PVC modified with 10 percent acrylic elastomeric impact modifier reduces the melt viscosity while not significantly changing the DTUL or the impact strength at room temperature. The use of PGT in impact modified PVC compositions is also helpful in matching the refractive index of the phases to provide the most esthetic appearance of such products as blow-molded bottles.

EXAMPLE 5 Blends of various amounts of PGT (2,500) and PVC (68-73) were milled at 360 F. for approximately 2 minutes. The blend was removed, granulated, dried for 16 hours at C. and injection molded at 360 to 380 F. into a mold maintained at about room temperature. Typical physical properties obtained from these test specimens are listed in Table X:

TABLE X Effect of Concentration of PGT in PVC on Physical Properties Tensile Tests Ten- Elong- Maxi- Modusile DTUL ation at mum lation of Composition Impact at 264 Maximum Stress Elasticity PVC PGT (ft-lb/ psi, Stress (psi) (psi) 1112) l. 100 0 26.7 65.7 3.01 8572 479,000 2. 10 126.5 67.7 2.98 8414 446,000 4. 82.5 17.5 170.1 66.0 3.23 8421 432,000 5. 75 25 183.7 65.3 3.30 8498 426,000 6. 60 40 83.1 67.0 3.25 8985100 7. 14.1 73.0 3300 370,000

EXAMPLE 6 Blends of 75 parts PVC of various molecular weights were blended with 25 parts PGT (1,6001,700), 1 part dibutyltin mercaptopropionol (DBTMP), and 0.5 part glycerol monostearate (GMS), and processed through screw extrusion and injection molding equipment. Typical processing and physical characteristics are shown in Table Xl.

r TABLE X! PVC Fikentscher K-Value 57 68 72-73 Extrusion Conditions Temperature Profile across the 1" Extruder ("F) Zone 1 330 330 330 Zone 2 350 350 350 Zone 3 370 370 370 370 370 370 Screw Speed (rpm) 175 175 175 Vacuum Reading (in. of Hg.) 27 27 27 Injection Molding Conditions Cyl. Temp.(F) 340 370 385 Block Temp. (F) 150 150 150 Pressure (lbs/in on 76" 400' 600 600 ram) Physical Test Properties Melt Flow Viscosity (400 F/ 100 sec-, poises). 2120 3600 4080 Impact:

Izod unnotchedjgllgr (ft-lbs) l7 18 22 Izod notched, W bar (ft-lbs) 0.3 0.4 0.4 Izod molded notch, bar (ft-lbs) 0.3 0,3 Charpy unnotched 8 13 (ft/ lbs/ A" X 1") Tensile Tests: I

Maximum Elongation 3.3 3.3 3.3 Maximum Stress (psi) 8900 9000 9000 Modulus of Elasticity (psi) 446,000 451,000 442,000 Flexural Strength:

Maximum Strain (in/in) 0.042 0.043 0.044 Maximum Stress (psi) 482,000 505,000 474,000

EXAMPLE 7 Blends of 80 parts PVC (72-73), 1 part DBTMP and parts of various polyesters were milled for 7 minutes and compression molded at 350 F. Typical physical characteristics for these moldings are shown on Table posure demonstrating improved resistance to exposure of the PGT modified composition are presented in Table XIII.

TABLE XIII Ultraviolet Light Resistance (Fadeometer) of PVC and Blends with Modifiers Exposure for Exposure f0r0Hr- Exposure for 100 Hrs. 500 Hrs.

v Modifier W.L.* Haze Color W. L. Haze Color W.L. Haze Color PGT 85.7 6.4 Clear 84.2 6.5 S]. 82.5 7.3 Yellow (I400) Yellow PGS 82.8 8.2 Yellow 83.2 8.1 Yellow 73.5 5.5 Brown None 85.0 6.9 Clear 82.6 8.7 Sl. 74.2 14.4 Brown 1 Brown WI. is total white light transmittance.

We claim: v

1. An intimately mixed plastic composition of improved processing characteristics and physical characteristics, comprising a. a polyvinyl chloride composition and b. a polyester of the formula Where A is the residue of terephthalic acid or mixture of dibasic acids selected from the group consisting of terephthalic acid and other dibasic acids, wherein A is at least 75 mole percent terephthalic acid;

G is the residue of 1,2-propylene glycol or mixtures of diols, wherein G is at least 75 mole percent 1,2- propylene glycol, and

n is such that said polyester is further characterized by a number average molecular weight in the range of about 1,200 to 4,000.

TABLE XII [Efiect of polyester compositions on physical characteristics of PVC/polyester blend] Clarity Gardner- Holdt; n DIUL Izod Percent Percent Polyester Viscosity 1 M polses C.) impact WL Haze 1,2-propylene/ethylene (100/0) terephthalate A-B 74 1. 0 84. 5 8. 0 1,2-propylene/ethylene (90/10) terephthalate. 71 79. 8 11. 7 1,2-propylene/ethylene (80/20) terephtlialate 66 0.8 82. 0 9. 6 1,2-propylene/ethylene (/50) terephthalatm. 74. 0 14. 9 1,2-propylene/ethylene (25/75) terephthalate 70 0.4 21. 8 100 1,2-propylene/ethylene (10/90) terephthalate i 0.4 1,2-propy1ene/ethylene (0/100) terephthalate Opaque Ethylene isophthalate 70 0. 4 1,2-pr0pylene isophthalate 67 78. 2 12. 3 1,3-butylene isophthalat 61 63. 5 18. 9 Do 66 0. 6 83. 5 7. 8 1,3-butylene terephthalate 65 78. 4 12.0 1,2-propylene/ethylene (50/50) 150 hthalat 64 58. 5 61. 3 Ethylene isophthalate/terephtha ate (50/50) 71 0.3 0 He Ethylene isophthalate/tere hthalate (ms/75)..-- 71 o. a Paq 1,2-propylene isophthalate terephthalate (50/50). 69 0. 4 73. 5 18. 4 1 2-propylene sebacate 3, 500 45 0. 3 82. 0 7. 3 one 7, 000 73 1. 2 87.0 5. 7

1 =25% in tetraehloroethane.

2 =Determined in a Sleglafi-MeKelvey rheometer at 400 3 =Total whote light transmittance.

The composition containing PGT exhibited considerably better mill processing behavior of the other polyesters listed in Table XII EXAMPLE 8 Blends of parts PVC (68), 1 part DBTMP, 0.5

I part GMS and 20 parts of the modifier, if any, were processed as in Example 7 and exposed continuously to high intensity ultraviolet light-Typical results to this ex- F. and a shear rate of 10 secr 2. The plastic composition of claim 1 wherein A is j I4 glycol, and neopentyl glycol.

8. The plastic composition of claim 1 which includes an alkyl methacrylate-butadiene/styrene graft polymer impact modifier. 

2. The plastic composition of claim 1 wherein A is the residue of terephthalic acid and G is the residue of 1,2-propylene glycol.
 3. The plastic composition of claim 1 wherein n is chosen so as to provide a number average molecular weight in the range of about 1,300 to 2,500.
 4. An injection-molded product of claim
 3. 5. An extruded product of claim
 1. 6. A rigid sheet of claim
 1. 7. The plastic composition of claim 1 wherein up to 25 mole percent of A is chosen from the group consisting of isophthalic acid and orthophthalic acid or anhydride, and up to 25 mole percent of G is chosen from the group consisting of ethylene glycol, 1,3-butylene glycol, and neopentyl glycol.
 8. The plastic composition of claim 1 which includes an alkyl methacrylate-butadiene/styrene graft polymer impact modifier. 